Spark advance system



May 5, 1964 C. R. GOODYEAR SPARK ADVANCE SYSTEM Filed March 9, 1962 K .m A f L M m@ .a 6.. R. @ai AO M an R M cm T11 E f L m W E M M M, H H w f f R p M w 1 w M A "III United States Patent O .3,131,681 SPARK ADVANCE SYSTEM Charles R. Goodyear, Birmingham, Mich., assign'or to Ford Motor Company, Dearborn, Mich., a corporation of Delaware Filed Mar. 9, 1962, Ser. No. 178,750 5 Claims. (Cl. 12S-117) This invention relates to vacuum spark advance systems for internal combustion engines.

For maximum operating efiiciency, the spark of an internal combustion engine is advanced somewhat for higher engine speeds and for part throttle operation in which the engine is under relatively light load. It is usual to advance the spark responsive to the degree of vacuum in the carburetor or intake manifold as well as responsive to engine speed. The present invention is directed to an advance system operating solely in response to carburetor and intake manifold vacuum.

According to the present invention, the spark advance of an engine is closely controlled to obtain the desirable amount of advance at both part and wide open throttle throughout the entire range of engine speeds. This is obtained by connecting the usual vacuum-actuated timing control of the distributor to the air passage of the carburetor at the venturi and at the throttle bore immediately upstream of the throttle plate. By utilizing fixed orifices of predetermined size in the passages connecting the air passage of the carburetor with the distributor, together with an auxiliary orifice and passage which is operative only at full throttle, the desired degree of advance may be obtained at all engine speeds under both part and full throttle.

In the form shown of the present invention, a one-way valve of the ball check type is utilized to control flow of air through the auxiliary orifice. In such construction, the check valve prevents any flow of air through this passage except under conditions when there is greater vacuum at the venturi than at the throttle plate, as occurs at and near wide open throttle operation.

Among the objects of the present invention are to provide a simple and dependable full pressure spark advance system which will limit the advance at full throttle operation to a desired maximum and also maintain spark advance at part throttle within reasonable limits. Another object of the invention is to provide such a spark advance system which is simple and dependable in operation and economical to manufacture, and generally to improve spark advance systems of the type described.

Other objects, and the nature and scope of the invention will be more apparent from the detailed description to follow:

My invention is clearly defined in the appended claims. In the claims, as well as in the description, parts may at times be identified by specific names for clarity and convenience, but such nomenclature is to be understood as having the broadest meaning consistent with the context and with the concept of my invention as distinguished from the pertinent prior art. The best form in which I have contemplated applying my invention is illustrated in the accompanying drawings forming part of this specification in which:

FIGURE l is a diagrammatic cross section of a carburetor barrel embodying the control system of the present invention, the connection to the vacuum control of a timer being shown.

FIGURE 2 is a graph showing spark advance at both part and full throttle at various engine speeds in a typical embodiment of the invention.

Referring now to the drawings, the air intake portion of a carburetor is shown. This portion includes a venturi and a throttle bore 11 downstream of the venturi. A

3,131,681 Patented May 5, 1964 throttle valve 12 of the buttery type is mounted in the throttle bore 11 and is manually movable between closed full line position and open broken line position to control the amount of air-fuel mixture passing to an engine to thus control engine speed.

A timer 14, which may be of the distributor type, times the spark for the engine. This timer, which is provided with a vacuum controlled advance which may be substantially the same as that shown in Mallory Patent 2,659,35 3, has a flexible diaphragm 15, one side of which is exposed to a partial Vacuum from the carburetor as will be explained, and the other side of which is exposed to atmospheric pressure. The timer is constructed so that increasing the vacuum (lowering the pressure on the carburetor side of the diaphragm) advances the spark. A spring, not shown, in the timer works in opposition to the vacuum advance, tending to retard the spark.

The diaphragm 15 is contained within a chamber 16, one side of which is connected with the venturi 10 of the carburetor through a passage 17. Preferably, a fixed orifice 19 of reduced diameter is located at the venturi end of the passage.

The passage 17 extending between the venturi 10 and the diaphragm 15 is connected with the throttle bore immediately upstream of the throttle plate by a second passage 20. Preferably, there is a fixed orifice 21 at the throttle bore and a fixed orifice 22 where the passage 20 opens into the passage 17 to meter the flow of air through the passage 20. The arrangement of the first passage 17 and the second passage 20 is such that whenever the pressure at the venturi and at the orifice 21 in the throttle bore differs, the partial vacuum impressed on the diaphragm 15 will be somewhere between these two values. To accomplish this, air will flow one direction or the other through the second passage 20 so as to either increase or decrease the vacuum impressed on the diaphragm through the orifice 19 at the venturi.

When the throttle is in closed position as indicated in the full line position of FIGURE l, pressure at the venturi 10 and above the throttle plate is nearly atmospheric and there will be little spark advance. This is indicated by the point L of the diagram of FIGURE 2. The pressure at the venturi 16 decreases (vacuum increases) with increasing engine speed due to the increased velocity of air therethrough. At part throttle, the pressure downstream of the throttle plate is substantially less than the pressure upstream of the throttle plate. Accordingly, as the edge of the throttle plate moves past the orifice 21, the pressure at the orifice is substantially reduced. The pressure at the orifice 21 increases from part throttle towards full throttle position until between half and full throttle the pressure exceeds the pressure at the orifice 19. At this time, the ow of air, which initially is downwardly through the second passage 20 to the orifice 21, reverses and reduces somewhat the vacuum impressed on the diaphragm 15 of the timer by the passage 17 Flow through the second passage 20 is restricted by the fixed orifice 22. In order to reduce the spark advance for wider throttle openings, a third passage 24, in parallel with the fixed orifice 22 and connecting the passage 17 with the throttle bore through the passage 20, is provided. This third passage has the effect of increasing the size of the orifice 22 so as to give greater effect to the pressure at the throttle bore. This passage is provided with a one way valve which preferably consists of a steel ball 25 received on a valve seat 26 in the third passage. A concentric rod 27 in the passage holds the ball 25 against displacement into the passage 17. Preferably, the passage 24 also has a metering orifice 23.

The third passage 24 is closed at all times except when the pressure at the throttle bore exceeds pressure at the venturi suiciently to unseat the ball 25 against the force of gravity, at which time the area of the third passage will reduce the vacuum impressed on the diaphragm 1S by the venturi and therefore retard the spark.

The above system permits a full pressure or vacuum spark advance system in which the spark advance at full throttle operation and top speed, represented by the point H, is held to a desirable limit without the part throttle curve extending upwardly in the intermediate engine speeds so as to provide excessive spark advance.

I claim:

1. In an internal combustion engine, the combination of an ignition timer operable through a given range to advance and retard the ignition spark responsive to degree of vacuum, a carburetor having an intake passageway provided with a venturi, a throttle bore downstream of the venturi, a butterfly-type throttle valve within the throttle bore, a first air passage connecting the venturi with the timer for controlling spark timing, a second air passage extending between the first passage and the throttle bore immediately upstream of the throttle valve when in closed position and having a fixed orifice, an additional passage in parallel with the fixed orifice and connecting the throttle bore with the first passage, and a one-way valve in the additional passage permitting fiow only in the direction from the throttle bore to the first passage.

2. In an internal combustion engine, the combination of an ignition timer operable through a given range to advance and retard the ignition spark responsive to degree of vacuum, a carburetor having an intake passageway provided with a venturi, a throttle bore downstream of the venturi, a butterfly-type throttle valve within the throttle bore, a first air passage connecting the venturi with the timer for controlling spark timing, a second air passage extending between the first passage and the throttle bore immediately upstream of the throttle valve when in closed position and having a fixed orifice, an additional passage in parallel with the fixed orifice and connecting the throttle bore with the first passage, and a ball check valve in the additional passage permitting fiow only in the direction from the throttle bore to the first passage.

3. In an internal combustion engine, the combination of an ignition timer operable through a given range to advance and retard the ignition spark responsive to degree of vacuum, a carburetor having an intake passageway provided with a venturi, a throttle bore downstream of the venturi, a butterfly-type throttle valve Within the throttle bore, a first air passage connecting the venturi with the timer for controlling spark timing, a second air passage extending between the first passage and the throttle bore immediately upstream of the throttle valve when in closed position and having a fixed orifice, an additional passage in parallel with the fixed orifice and connecting the throttle bore with the first passage, and a one-way valve and fixed orifice in the additional passage permitting flow only in the direction from the throttle bore to the first passage.

4. In an internal combustion engine carburetor having an intake passage provided with a venturi, a throttle bore downstream of the venturi and a butterfiy-type throttle valve within the bore: a full pressure spark advance system including a first passage extending from the venturi, a second passage extending from the throttle bore immediately upstream of the throttle valve and communicating with the first passage through a fixed orifice, an additional passage in parallel with the fixed orifice and connecting the throttle bore with the first passage, and a one-way valve in the additional passage permitting flow only in the direction from the throttle bore into the first passage.

5. In an internal combustion engine carburetor having an intake passage provided with a venturi, a throttle bore downstream of the venturi and a butterfly-type throttle valve Within the bore: a full pressure spark advance system including a first passage extending from the venturi, a second passage extending from the throttle bore immediately upstream of the throttle valve and communicating with the first passage through a fixed orifice, an additional passage in parallel with the fixed orifice and connecting the throttle bore with the first passage and a one-way valve and fixed orifice in the additional passage permitting fiow only in the direction from the throttle bore into the first passage.

References Cited in the file of this patent UNITED STATES PATENTS 2,365,768 Mallory Dec. 26, 1944 2,621,641 Sterner Dec. 16, 1952 3,021,828 Frank Feb. 20, 1962 3,051,150 Johnson et al Aug. 28, 1962 

1. IN AN INTERNAL COMBUSTION ENGINE, THE COMBINATION OF AN IGNITION TIMER OPERABLE THROUGH A GIVEN RANGE TO ADVANCE AND RETARD THE IGNITION SPARK RESPONSIVE TO DEGREE OF VACUUM, A CARBURETOR HAVING AN INTAKE PASSAGEWAY PROVIDED WITH A VENTURI, A THROTTLE BORE DOWNSTREAM OF THE VENTURI, A BUTTERFLY-TYPE THROTTLE VALVE WITHIN THE THROTTLE BORE, A FIRST AIR PASSAGE CONNECTING THE VENTURI WITH THE TIMER FOR CONTROLLING SPARK TIMING, A SECOND AIR PASSAGE EXTENDING BETWEEN THE FIRST PASSAGE AND THE THROTTLE BORE IMMEDIATELY UPSTREAM OF THE THROTTLE VALVE WHEN IN CLOSED POSITION AND HAVING A FIXED ORIFICE, AN ADDITIONAL PASSAGE IN PARALLEL WITH THE FIXED ORIFICE, AND CONNECTING THE THROTTLE BORE WITH THE FIRST PASSAGE, AND A ONE-WAY VALVE IN THE ADDITIONAL PASSAGE PERMITTING FLOW ONLY IN THE DIRECTION FROM THE THROTTLE BORE TO THE FIRST PASSAGE. 